* Nikkei regains ground lost on profit-taking after the BOJ * Hitachi, Komatsu up after maintaining outlook guidance * Fuji Heavy Industries jumps after lifting earnings guidance By Dominic Lau TOKYO, Oct 31 (Reuters) - Japan's Nikkei share average advanced on Wednesday as investors took comfort that some firms, such as Hitachi Ltd and Komatsu Ltd, did not cut their full-year earnings guidance as feared. Index heavyweight Fanuc Corp, which gained 1.6 percent, also lent support to the index after its client and Apple Inc supplier Hon Hai Precision Industry posted strong third-quarter results. The Nikkei rose 1 percent to 8,928.29 points, regaining ground which was lost in the previous session after the Bank of Japan eased policy in line with expectations, disappointing some who had hoped the central bank would take bolder steps to lift the economy out of deflation. Wednesday's gain helped the benchmark to end the month 0.7 percent higher, its third straight monthly gain. The Nikkei is up 5.6 percent this year. "We obviously had that sell-off yesterday after the BOJ ... We are seeing a bit of buying," a senior trader at a foreign bank said. "I guess yesterday's results were perhaps a little bit better than expected." Komatsu climbed 3.2 percent after the construction machinery maker maintained its full-year operating profit forecast, easing concerns it would cut its outlook when it reported first-half results after the market close on Tuesday. Many firms have slashed their profit forecasts this earnings season as a stuttering global growth and a boycott of Japanese products in China over a territorial dispute threatens revenues. Electrical machinery maker Hitachi and electronics parts manufacturer Omron Corp also reassured investors by retaining their full-year earnings outlooks. Hitachi gained 3.2 percent and Omron gained 5.1 percent. Fuji Heavy Industries jumped 6.7 percent to an 11-year high a fter the carmaker hiked its annual operating profit forecast by 22 percent. Sentiment also picked up on Wednesday after the yen did not firm as much as investors had feared it would, said Ryota Sakagami, chief strategist of equity research at SMBC Nikko Securities. "It's been rather unclear why the yen weakened so much recently, so it was encouraging to see that it's likely due to the U.S. recovery gathering momentum and not just expectations of easing," Sakagami said. The yen was at 79.575 yen to the dollar, down from Tuesday's high of 79.275 yen, a slight positive for exporters fretting about shrinking overseas profit due to an unfavourable exchange rate. Mobile operator Softbank Corp, the most-traded stock on the main board by turnover, added 0.8 percent and consumer electronics maker Panasonic Corp jumped 4.5 percent ahead of their results after the market close. After the bell, Panasonic reported a 16 percent gain in second-quarter operating profit as it moves away from loss-making TVs in favour of batteries, household appliances and other businesses outside its struggling consumer electronics mainstay. EARNINGS IN FOCUS But some market participants said they did not have much faith in the index's gains as Wall Street has been closed for two days due to a massive storm and there was uncertainty about how U.S. markets would react to the disaster later in the day. "Results from exporters are not looking good, which makes me think recent gains, including today's, are a bit filmsy," said Norihiro Fujito, senior investment strategist at Mitsubishi UFJ Morgan Stanley. As of Monday, 63 percent of the 27 Nikkei companies that have reported quarterly earnings so far had undershot market expectations, according to Thomson Reuters StarMine. That compared with 54 percent in the previous quarter. Ricoh Co Ltd dropped 3.1 percent after the office equipment maker missed guidance for its interim operating profit. Brewer Asahi Group Holdings slipped 1.7 percent on concerns that the company may fall short of its full-year operating profit forecast after it reported weak nine-month results. A survey of 10 Japan-based fund managers showed allocations for Japanese equities slipped to 33.9 percent this month from 34.7 percent in September, marking its fourth straight month of decline. The broader Topix index gained 1.2 percent to 742.33 in relatively active trade, with 1.82 billion shares changing hands, down f r om Tuesday's nearly two-week high of 2.04 billion shares but up from last week's average of 1.66 billion.